Perrhenate Esters as Intermediates in Molecular Complexity-Increasing Reactions.

Allylic alcohols form perrhenate esters upon reaction with Re2 O7 or HOReO3. These species undergo nonstereospecific and nonregiospecific alcohol-transposition reactions through cationic intermediates. Sequencing these nonselective processes with reversible trapping by electrophiles results in cyclization reactions where regio- and stereocontrol are dictated by thermodynamics. The cationic intermediates can also be utilized as electrophiles in intra- or intermolecular dehydrative reactions with nucleophiles. These processes serve as the basis for applications in catalytic syntheses of a wide range of heterocyclic and carbocyclic structures that often show considerable increases in molecular complexity. This Account describes a sequence of events that started from a need to solve a problem for the completion of a natural product synthesis and evolved into a central element in the design of numerous new transformations that proceed under mild conditions from readily accessible substrates. 1 Introduction 2 Exploratory Studies 3 Application to Spiroketal Synthesis 4 Reactions with Epoxides as Trapping Agents 5 Development of Dehydrative Cyclizations 6 Bimolecular Reactions 7 Spirocyclic Ether Formation 8 Conclusions [ABSTRACT FROM AUTHOR]